The present disclosure relates to a transaction method and a transaction system. Systems that let a user start a game in an amusement arcade such as a casino by exchanging electronic data between a user's mobile terminal and a game machine installed in the amusement arcade are known. For example, Japanese Unexamined Patent Application Publication No. 2002-315946 discloses an apparatus which receives a money value data balance from a mobile terminal and lends game mediums corresponding to the money value data balance.
Because casinos are commonly built in a space without windows in a building, radio waves of mobile phone networks are less likely to be received in the building. Further, because there are many game machines and mobile terminals capable of connecting to Wi-Fi channels in a casino, the Wi-Fi channels are crowded. Therefore, it is difficult for a mobile terminal in the casino to communicate with a server by using wireless communication channels. When a player tries to start playing a game in such a poor wireless communication environment, there are cases where the mobile terminal cannot connect with the server. In such a case, the possibility that the player will give up playing the game is high. If the player gives up playing the game, a casino misses out on earning profits. Therefore, it is necessary to minimize the possibility that the casino misses out on the profits, while also maintaining security.
In this situation, it is effective for a mobile terminal to exchange electronic data with the server through a game machine which can communicate with the server. It is effective to use a short distance wireless communication technology such as the Bluetooth Low Energy (BLE) and the Near Field Communication (NFC) for communication between the mobile terminal and the game machine to prevent interference with other mobile terminals.
However, a third person may intercept the electronic data when the electronic data is exchanged between a user's mobile terminal and the game machine using the short distance wireless communication such as BLE. Therefore, high security is required for exchanging the electronic data.
Further, because many game machines are installed in the amusement arcade, the mobile terminal can communicate with a plurality of game machines at the same time. For this reason, it is necessary that the mobile terminal correctly communicates with the game machine with which the user wants to play so that the user can reliably start playing a game with the game machine.